A hydrostatic actuator system includes an electric motor for delivering a hydraulic fluid via a piston unit. The actuator system is operating using a method in which a change in volume caused by a temperature change is sensed by a pressure measurement. The method reliably identifies a state of the transfer of the hydraulic fluid from a planetary roller transmission compartment into the master piston. The pressure measurement is continuously evaluated, and, in the event of a negative signal of the pressure measurement, suction of the hydraulic fluid by a planetary roller transmission lying in the hydraulic fluid between the electric motor and the piston unit into the piston unit is recognized and a fault signal is output.

A hydrostatic actuator system includes an electric motor for delivering a hydraulic fluid via a piston unit. The actuator system is operating using a method in which a change in volume caused by a temperature change is sensed by a pressure measurement. The method reliably identifies a state of the transfer of the hydraulic fluid from a planetary roller transmission compartment into the master piston. The pressure measurement is continuously evaluated, and, in the event of a negative signal of the pressure measurement, suction of the hydraulic fluid by a planetary roller transmission lying in the hydraulic fluid between the electric motor and the piston unit into the piston unit is recognized and a fault signal is output.

Multiport pumps and associated pumping systems are described that provide a selective hydraulic or electrically powered pump/pump system. The pumps provide movement within a device or larger system. Movement can cause compression/expansion of a fluid and provide fluid movement within the same device or system. In this instance, the volume of fluid and the fluid flow path within, from, and to the pump(s) is kept constant to reduce or eliminate cavitation, seizure, and/or hydraulic lock. Use of at least one reservoir comprising; a compensator tank, a port allowing for operation at ambient pressure, and a pressure measuring device measuring pressure allowing for unbalanced flow to and from the multiport pumps along with thermal expansion or compression is detailed. In addition, use of a multiport swashplate pumps and associated valve plates that incorporate the features and functions of several valves not heretofore provided within the pump itself is also described.

Multiport pumps and associated pumping systems are described that provide a selective hydraulic or electrically powered pump/pump system. The pumps provide movement within a device or larger system. Movement can cause compression/expansion of a fluid and provide fluid movement within the same device or system. In this instance, the volume of fluid and the fluid flow path within, from, and to the pump(s) is kept constant to reduce or eliminate cavitation, seizure, and/or hydraulic lock. Use of at least one reservoir comprising; a compensator tank, a port allowing for operation at ambient pressure, and a pressure measuring device measuring pressure allowing for unbalanced flow to and from the multiport pumps along with thermal expansion or compression is detailed. In addition, use of a multiport swashplate pumps and associated valve plates that incorporate the features and functions of several valves not heretofore provided within the pump itself is also described.

In order to provide a master cylinder, in particular for a clutch system, an actuating system or a braking system of a vehicle, which enables secure sealing of the cylinder chamber relative to the outside, as well as a reliable flow of hydraulic medium into the cylinder chamber, it is proposed that the piston comprises a first section which has a cylindrical lateral surface and a second section which has at least one region which is set back radially inwardly with respect to the cylindrical lateral surface of the first section, wherein at least one set-back region extends to an end of the piston and wherein the first and second sections are arranged on the piston in such a way that in an actuating position of the piston, the main sealing element in the first section of the piston abuts in sealing manner thereagainst and in the pressure equalization position of the piston, in the second section of the piston between the piston and the main sealing element, at least one gap is formed, through which hydraulic medium can flow along the piston from the supply chamber into the cylinder chamber in order to equalize the pressure.

In order to provide a master cylinder, in particular for a clutch system, an actuating system or a braking system of a vehicle, which enables secure sealing of the cylinder chamber relative to the outside, as well as a reliable flow of hydraulic medium into the cylinder chamber, it is proposed that the piston comprises a first section which has a cylindrical lateral surface and a second section which has at least one region which is set back radially inwardly with respect to the cylindrical lateral surface of the first section, wherein at least one set-back region extends to an end of the piston and wherein the first and second sections are arranged on the piston in such a way that in an actuating position of the piston, the main sealing element in the first section of the piston abuts in sealing manner thereagainst and in the pressure equalization position of the piston, in the second section of the piston between the piston and the main sealing element, at least one gap is formed, through which hydraulic medium can flow along the piston from the supply chamber into the cylinder chamber in order to equalize the pressure.

The invention relates to a hydraulic transmission unit for an actuator, which hydraulic transmission unit can be filled with a hydraulic fluid and has a first and a second chamber which are hydraulically interconnected and of which one is designed as a drive chamber and the other one is designed as an output chamber. At least in the first chamber, a piston is arranged movably along a piston axis, such that this piston subdivides the first chamber into a variable-volume working chamber and a rear-side chamber, the rear-side chamber being delimited at least partially by a bellows element having a variable axial length. The invention further relates to an actuator having such a hydraulic transmission unit.

The invention relates to a hydraulic transmission unit for an actuator, which hydraulic transmission unit can be filled with a hydraulic fluid and has a first and a second chamber which are hydraulically interconnected and of which one is designed as a drive chamber and the other one is designed as an output chamber. At least in the first chamber, a piston is arranged movably along a piston axis, such that this piston subdivides the first chamber into a variable-volume working chamber and a rear-side chamber, the rear-side chamber being delimited at least partially by a bellows element having a variable axial length. The invention further relates to an actuator having such a hydraulic transmission unit.

An accumulator includes a housing, a flexible bladder and a support. The housing includes a chamber having a defined volume and a passage extending through the housing. The flexible bladder is positioned within the chamber and contains a compressible gas. The bladder being operable in an expanded condition and a partially collapsed condition. The support is positioned in the chamber and engages the flexible bladder when the flexible bladder is in the expanded condition. Liquid is positioned in the chamber and in contact with the flexible bladder. A volume of the liquid within the chamber is at a minimum when the flexible bladder is in the expanded condition. The volume of liquid within the chamber increases as a pressure of the liquid increases to compress the gas and operate the flexible bladder in the partially collapsed condition.

An accumulator includes a housing, a flexible bladder and a support. The housing includes a chamber having a defined volume and a passage extending through the housing. The flexible bladder is positioned within the chamber and contains a compressible gas. The bladder being operable in an expanded condition and a partially collapsed condition. The support is positioned in the chamber and engages the flexible bladder when the flexible bladder is in the expanded condition. Liquid is positioned in the chamber and in contact with the flexible bladder. A volume of the liquid within the chamber is at a minimum when the flexible bladder is in the expanded condition. The volume of liquid within the chamber increases as a pressure of the liquid increases to compress the gas and operate the flexible bladder in the partially collapsed condition.